Apparatus for forming plastic strips



Feb. 3, 1953 R. c. RAHM 2,627,085

APPARATUS FORFORMING PLASTIC STRIPS Filed July 21, 1948 2 SHEETS-SHEET 1 Q wvw (lttornegs Feb. 3, 1953 R. c. RAHM APPARATUS FOR FORMING PLASTIC STRIPS 2 SHEETS-SHEET 2 Filed July 21, 1948 Patented Feb. 3, 1953 UNITED STATES PATENT OFFICE (Cl. IS -9) 4 Claims;

This invention relates to equipment for use in the fabrication of strip stock from plastic materials, especially from the synthetic linear polyamides known to the trade as nylon. The invention is particularly concerned with the mounting and drive arrangements for a pair of forming rolls employed in equipment of the character referred to.

As disclosed in the copending application of Eugene E. Montross, Serial No. 767,282, filed August 7, 1947, issued as Patent No. 2,585,155 on February 12, 1952, equipment of this type comprises a pair of forming rolls arranged with lower portions thereof immersed in a liquid cooling bath. Molten polyamide material, for instance polyhexamethylene adipamide or polyhexamethylene sebacamide is delivered to the entrance nip of the forming rolls from a point above the liquid level in the cooling bath, and the material is concurrently rolled and solidified as it passes through the rolls into the liquid cooling bath.

It has been found that in producing strip stock by means of equipment of the genera1 type referred to, there is a tendency to deliver a strip stock product with a wavy surface, so that the product. is characterized by transverse ripples. According to the present invention, this tendency is overcome by an improved mounting;

and driving arrangement for the forming rolls. The. mounting for the rolls according to the invention is exceptionally sturdy and the drive mechanism provides positive and accurate. drive for hothrolls. This is accomplished in the equipment of the invention while at the. same, time making provision for adjustment of the rolls toward and away from each other, whereby to provide for adjustment of the thickness of the strip stock being formed.

The equipment of the present invention also provides a particularly desirable arrangement of driving and adjusting parts located exteriorly of the cooling bath in which the rollsare partially submerged, whereby to simplify problems of lubrication and the like.

How the foregoing and other objects and advantages are attained will appear more fully from the following description referring to. the accompanying drawings, in which.

Figure 1 is a somewhat diagrammatic. vertical sectional view through portions of stripv forming equipment of the type to which the invention is particularly applicable;

Figure 2 is a top plan view of. the roll mounting, driving and adjusting mechanism of the presentinvention; and

Figures 3 and. 4 are. elevational views of the equipment shown in Figure 2, taken respectively 2 from. the. bottom and from the left hand side of. Fi'gureZ.

Referring first to Figure 1, a pair of forming. rolls. 5$ having mounting shafts l and 8 are mounted so as to be partially submerged below the liquid level L of a liquid cooling bath, for instance a water bath, contained within the vessel 9; Polyamide material in flake or granular form is introduced into the hopper it of the feeder mechanism which comprises. a feed screw ll arranged within a casing [2 having inset electrical heater elements 13. The heater elements raise the temperature of the material to the molten state and the molten polyamide is discharged through the nozzle Hi into the entrance nip of the rolls 5 and 6. As the material passes between the rollsv it is chilled and solidified and formed into the strip indicated at S which passes down wardly inthe cooling bath around a guide It? and from there over guide. it, out of the bath to' the rolls ill8. Rolls I? and I3 serve to maintain some tension on the strip S as it is drawn from forming rolls 5-45. The frictional characteristics and pressure of engagement of the rolls l1 and I8, however, is such as to permit slippage.

As seen in Figures 2, 3 and 4, the roll mounting comprises a mounting frame having side frame members |92i1 and 2l-22 arranged as spaced parallel pairs and interconnected at their ends to form a centrally open square. As seen in Figure 3, the members l9'29' are provided with laterally projecting flanges serving as supporting elements which are adapted to rest upon the upper-edges of the vessel Q for the liquid cooling The shaft l for roll 5 is carried by movable mounting members 26 having bearing blocks at their lower ends with which the bearing caps 21 cooperate. A transverse tie bar 28 interconnects the two bearing caps 21. 26 are also interconnected at their upper ends by a tie member 29, and the assembly of the various mounting parts for the roll 5 issuspended from the threaded portions 30 of a pair of adjusting screws 3!, one located at each side of The mountin members 26 have the. machine. threaded apertures cooperating with the threaded portions 30 of the screws 3|. adjusting screws. 3|. is. supported by a pair. of

The members Each of thestandards 32 and 33 which are mounted on the side frame members |9 (at one side) and (at the other side). To prevent axial movement of each adjusting screw 3| the screw is shouldered adjacent the standard 32 and is provided with an abutment 34 fixed thereto at the opposite side of the standard 32. Standard 33 is of split construction and is provided with a tightening screw 35 by means of which any adjusted setting of the screw may be retained. Each adjusting screw is provided with a knurled operating knob 36. By means of this supporting and adjusting mechanism for the roll 5, roll 5 may be moved toward and away from roll 6, to thereby regulate the thickness of the strip stock being formed.

The drive mechanism for the rolls includes a drive shaft 31 extended across the mounting frame and journaled in bearings supported by brackets 3838. This shaft is carried at an elevation substantially above the mounting frame so that one end of the shaft 31 (the right hand end when viewed as in Figures 2 and 3) may readily be extended above and beyond the upper edge of the vessel 9 for the liquid cooling bath. This end of the shaft 31 is thus adapted to receive power from any suitable motor, preferably incorporating a variable speed drive. The shaft 31 carries a pair of helical gears 3939 meshing with complementary gears 40 which are fixed on the two drive shafts 4|, one of Which is arranged at each side of the machine. Each of shafts 4| is mounted by means of a bearing 42 toward one end thereof which is carried by one of the side frame members. Toward the other end each of shafts 42 is journaled in a lower portion of the standard 33. Each shaft 4| further carries two worms 43 and 44 positioned to mesh with complementary worm wheels 45 and 46 which are fixed respectively on the roll shafts and 8.

It will be noted that the worms 43 lie between the standards 32 and 33 and are of sufficient dimension axially of shafts 4| so as to retain proper driving interengagement with the worm wheels 45 regardless of adjustment of the movable mounts for the roll 5 to bring this roll toward and away from roll 6.

From the foregoing it will be noted that the supporting framing for the rolls comprises supporting elements or side frame members which are spaced from each other and arranged to straddle the liquid cooling bath. It will be seen, moreover, that the rolls themselves are suspended or slung from the frame and other mounting parts so as to provide for operation of the rolls partly below the level of the liquid in the cooling bath. All of the driving parts, however, except for the worm wheels 45 and 46 are mounted on the framing at an elevation above the cooling liquid.

The arrangement of the roll mounting, roll driving and roll adjusting mechanisms is further of advantage since these mechanisms are all carried on a unitary framing, so that the entire operating mechanism comprises a unit which in itself provides sturdy support and accurate drive for the rolls, entirely independently of the walls of the vessel for the cooling bath.

The employment of the particular worm and worm wheel drive for the rolls is of especial advantage in ensuring positive and accurate drive of the rolls, notwithstanding the provision for adjustment of the rolls toward and away from each other.

The adjustment mechanism is also of sturdy construction and is capable of highly accurate regulation of the thickness of strip stock to be formed. For the purpose of giving a visual indication of the spacing of the rolls, the abutment members 34 which are fixed to the inner ends of the adjustment screws 3| are provided with scale or graduation marks 41 which cooperate with fixed pointers 48, thereby providing a direct reading of the roll spacing. The arrangement of the invention provides for the production of strip stock of highly uniform dimensions, especially as to thickness, and this high degree of uniformity is retained notwithstanding adjustment to vary the thickness of the strip stock.

I claim:

1. Equipment for use in forming strip stock from plastic materials comprising, in combination with a liquid-containing vessel into which the formed strip stock is to be delivered, a supporting framing having spaced frame elements adapted to be positioned at the upper edges of said vessel, a pair of forming rolls slung downwardly from said framing, worm wheels fixed to rotate with said rolls, a driving shaft for the rolls extended perpendicularly to the axes of the rolls and their worm wheels, the driving shaft being mounted above the framing, and worms fixed on the driving shaft and meshing with the worm wheels at the tops of the latter.

2. Equipment according to claim 1 and further including movable mounting devices for one of the rolls providing for movement thereof toward and away from the other roll, and an adjustable support for said mounting devices located above the framing.

3. Equipment for use in forming strip stock and adapted for use with a liquid-containing vessel, said equipment comprising a supporting framing adapted to be removably mounted at the upper edge of the vessel, a pair of roll mountings for a pair of rolls suspended from and projecting downwardly from the framing, a pair of rolls carried by said mountings, the mountings for one of said rolls being shiftably movable toward and away from the mountings for the other roll and projecting above the framing, and mechanism for shifting said movable roll mountings comprising screw thread devices cooperating with the upward projections of the movable roll mountings above the framing.

4. Equipment according to claim 3 in which the movable roll mountings are suspended from the screw thread devices, and further including bracing members extended axially of the movable roll between the movable mountings therefor.

ROBERT C. RAHM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 324,399 McI-Iugh Aug. 18, 1885 727,229 Turner May 5, 1903 1,226,949 Clark May 22, 1917 1,591,170 Lutyens July 6, 1926 2,160,767 Wadsworth May 30, 1939 2,212,772 Graves Aug. 27, 1940 FOREIGN PATENTS Number Country Date 651,268 Germany Sept. 23, 1937 

